Posts tagged: Facebook Attack

A new configuration of the Carberp Trojan that targets Facebook users to commit financial fraud. Unlike previous Facebook attacks designed to steal user credentials from the log-in page, this version attempts to steal money by duping the user into divulging an e-cash voucher.

Carberp replaces any Facebook page the user navigates to with a fake page notifying the victim that his/her Facebook account is “temporarily locked”. The page asks the user for their first name, last name, email, date of birth, password and a Ukash 20 euro (approximately $25 US) voucher number to “confirm verification” of their identity and unlock the account. The page claims the cash voucher will be “added to the user’s main Facebook account balance”, which is obviously not the case. Instead, the voucher number is transferred to the Carberp bot master who presumably uses it as a cash equivalent (Ukash provides anonymity similar to that offered by cash payments), thus effectively defrauding the user of 20 euro/$25.

This clever man-in-the-browser (MitB) attack exploits the trust users have with the Facebook website and the anonymity of e-cash vouchers. Unlike attacks against online banking applications that require transferring money to another account which creates an auditable trail, this new Carberp attack allows fraudsters to use or sell the e-cash vouchers immediately anywhere they are accepted on the internet.

Attacking social networks like Facebook provides cybercriminals with a large pool of victims that can be fairly easily tricked into divulging confidential account information, and even, as illustrated in this case, giving up their cash. With the growing adoption of e-cash on the internet, we expect to see more of these attacks. Like card not present fraud, where cybercriminals use stolen debit and credit card information to make illegal online purchases without the risk of being caught, e-cash fraud is a low risk form of crime. With e-cash, however, it is the account holder not the financial institution who assumes the liability for fraudulent transactions.

Summary:
When using the Facebook ‘Messages’ tab, there is a feature to attach a file. Using this feature normally, the site won’t allow a user to attach an executable file. A bug was discovered to subvert this security mechanisms. Note, you do NOT have to be friends with the user to send them a message with an attachment.

Description:
When attaching an executable file, Facebook will return an error message stating:
“Error Uploading: You cannot attach files of that type.”

When uploading a file attachment to Facebook we captured the web browsers POST request being sent to the web server. Inside this POST request reads the line:

Content-Disposition: form-data; name=”attachment”; filename=”cmd.exe”

It was discovered the variable ‘filename’ was being parsed to determine if the file type is allowed or not.

To subvert the security mechanisms to allow an .exe file type, we modified the POST request by appending a space to our filename variable like so:

filename=”cmd.exe ”

This was enough to trick the parser and allow our executable file to be attached and sent in a message.

During last weekend a viral rogue app campaign hit Facebook again. This time the application was called “Profile Creeps” which, like many other rogue applications before it, promises to do what Facebook simply doesn’t allow *ANY* app to do – let us know who looks at our profile. But users are still tricked into installing apps that promise to do just this. And just like most others, the latest one leads to a survey that in the end generates money for the people behind the app.

let’s look at a very similar fraudulent application that “can” allow Facebook users to know who “creeps” at their profile, called “Facebook Profile Creeper Tracker Pro”. The application asks for some permissions, shows an online survey/advertisements and tells the user at the end of the process that he/she is the one that looks at his/her own profile the most. In other words, this application should be revoked according to the terms and conditions of Facebook.

This application was built with a pre-defined toolkit called “Tinie app” which is a Facebook viral application template available in some variations for only $25 or even less. The next image is one of the template images in the toolkit that aims to give some directions to the buyer, besides the full-blown step-by-step guide that comes with the kit itself:

The buyer doesn’t have to have development experience with Facebook, he/she just needs to follow the accompanying instructions and a working viral Facebook application is at their disposal.